Biosensor detects patient drug use

Researchers at Surrey University have developed a pilot biosensor that could give medical staff vital help in treating drug overdoses.

The device can determine in less than 10 minutes if a patient's blood contains a specific compound. Hospitals currently use lab tests that can take three hours.

The research is being carried out by a team under Dr. Sub Reddy, with backing from the Engineering and Physical Sciences Research Council.

The pilot sensor has been developed for paracetamol, and others are planned for alcohol and anti-depressants. It consists of a disc-shaped quartz crystal, measuring 1 cm in diameter and 0.2-mm thick.

"When an alternating electric field is applied the crystal vibrates from side to side, like a nanoscale earthquake," said Reddy. "It shakes 10 million times a second with an amplitude of a fraction of a nanometer."

A reaction chamber is placed above the surface of the crystal. When a blood sample is placed in the chamber, a series of chemical reactions can be made to occur so that if certain materials are present a solid forms on the crystal's surface. This solid then affects the frequency of the oscillation alerting medical staff that the compound is present in the bloodstream.